Manufacturing method of all-solid battery

Abstract

To provide a lithium deposition type all-solid battery, capable of providing means of improving a charge and discharge capacity.SOLUTION: A manufacturing method of an all-solid battery, comprises a power generation element having: a positive electrode having a positive electrode active material layer that contains a positive electrode active material and a negative electrode collector; a negative electrode in which a lithium metal is deposited onto the negative electrode collector at a charging; a solid-electrolyte layer that is interposed to between the positive electrode and the negative electrode, and contains a solid electrolyte; and a negative electrode intermediate layer that is interposed to between the negative electrode collector and the solid electrolyte layer, and contains a lithium reactive property material. The manufacturing method of the all-solid battery, contains: a first step of performing the charging until a predetermined capacity against an all-solid battery precursor as an uncharged state; and a second step of holding the all-solid battery precursor via the first step at a predetermined holding temperature and for a holding time.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing an all-solid-state battery. [Background technology]

[0002] In recent years, research and development into all-solid-state batteries (all-solid-state lithium secondary batteries) that use oxide- or sulfide-based solid electrolytes has been actively conducted. Solid electrolytes are materials that are mainly composed of ion conductors that can conduct ions in a solid state. For this reason, all-solid-state batteries have the advantage that, in principle, various problems caused by flammable organic electrolytes, as in conventional liquid-based lithium secondary batteries, do not occur. In addition, the use of high-potential, large-capacity positive electrode materials and large-capacity negative electrode materials can generally be used to significantly improve the output density and energy density of the battery.

[0003] As one type of all-solid-state battery, a so-called lithium precipitation type battery is known in which lithium metal is precipitated on the negative electrode current collector during charging. During the charging process of a lithium precipitation type all-solid-state battery, lithium metal is precipitated between the solid electrolyte layer and the negative electrode current collector to form a lithium metal layer, which is a negative electrode active material layer. Although such lithium precipitation type all-solid-state batteries have excellent energy density and output characteristics, they are prone to short-circuiting of the all-solid-state battery due to dendrites from the lithium metal layer and the resulting capacity reduction.

[0004] To address this problem, Patent Document 1 discloses a technique of providing a negative electrode intermediate layer containing amorphous carbon between the negative electrode current collector and the solid electrolyte layer. According to this document, this negative electrode intermediate layer functions as a protective layer for the lithium metal layer and inhibits the growth of dendrites from the lithium metal layer, thereby making it possible to inhibit short circuits and capacity reduction in the all-solid-state battery. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-96610 A

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, as a result of investigations by the present inventors, it has been found that sufficient charge and discharge capacity may not be obtained even when the techniques described in the above documents are applied.

[0007] Therefore, an object of the present invention is to provide a means for improving the charge and discharge capacity in a lithium precipitation type all-solid-state battery.

Means for Solving the Problems

[0008] One embodiment of the present invention includes a positive electrode having a positive electrode active material layer containing a positive electrode active material, a negative electrode having a negative electrode current collector, and lithium metal being deposited on the negative electrode current collector during charging, and a solid electrolyte layer interposed between the positive electrode and the negative electrode and containing a solid electrolyte, and a negative electrode intermediate layer interposed between the negative electrode current collector and the solid electrolyte layer and containing a lithium reactive material, and a manufacturing method of an all-solid-state battery including a power generation element having the same, and for an all-solid-state battery precursor having the same configuration as the all-solid-state battery and being in an uncharged state, a first step of charging up to a capacity C [mAh / cm 2 , and a second step of holding the all-solid-state battery precursor that has undergone the first step at a holding temperature T [°C] and a holding time t [hours], where the capacity C [mAh / cm 2 satisfies the following formula: Cx < C ≤ (Cx + Cy), where Cx [mAh / cm 2 is the capacity of the lithium reactive material per unit area of the negative electrode intermediate layer, and Cy [mAh / cm 2 is the capacity based on the voids per unit area of the negative electrode intermediate layer, and the holding temperature T [°C] and the holding time t [hours] satisfy the following formula: (T [°C] + 273) × ln(t [hours]) ≥ 1100, which is a manufacturing method of an all-solid-state battery.

Advantages of the Invention

[0009] According to the present invention, in a lithium precipitation type all-solid-state battery, the charge and discharge capacity is improved.

Brief Description of the Drawings

[0010] [Figure 1] FIG. 1 is a cross-sectional view schematically showing the overall structure of a laminated type (internal parallel connection type) all-solid-state lithium secondary battery (laminated secondary battery) according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0011] One embodiment of the present invention includes a positive electrode having a positive electrode active material layer containing a positive electrode active material, a negative electrode having a negative electrode current collector, and lithium metal being deposited on the negative electrode current collector during charging, a solid electrolyte layer interposed between the positive electrode and the negative electrode and containing a solid electrolyte, and a negative electrode intermediate layer interposed between the negative electrode current collector and the solid electrolyte layer and containing a lithium reactive material. A method for manufacturing an all-solid-state battery includes a first step of charging an all-solid-state battery precursor having the same configuration as the all-solid-state battery to a capacity C [mAh / cm 2 , and a second step of holding the all-solid-state battery precursor that has undergone the first step at a holding temperature T [°C] and a holding time t [hours], where the capacity C [mAh / cm 2 satisfies the following formula: Cx < C ≤ (Cx + Cy), where Cx [mAh / cm 2 is the capacity of the lithium reactive material per unit area of the negative electrode intermediate layer, and Cy [mAh / cm 2 is the capacity based on the voids per unit area of the negative electrode intermediate layer, and the holding temperature T [°C] and the holding time t [hours] satisfy the following formula: (T [°C] + 273) × ln(t [hours]) ≥ 1100. According to the manufacturing method according to this embodiment, in a lithium precipitation type all-solid-state battery, the charge and discharge capacity can be improved.

[0012] In the following, first, the overall structure of the all-solid-state battery manufactured by the manufacturing method according to the present embodiment will be described with reference to the attached drawings, and then the manufacturing method according to the present embodiment will be described. Note that the technical scope of the present invention should be determined based on the description of the claims, and is not limited to only the following embodiments.

[0013] FIG. 1 is a cross-sectional view showing a schematic overall structure of a stacked type (internal parallel connection type) all-solid-state lithium secondary battery (hereinafter, also simply referred to as a "stacked type secondary battery") according to one embodiment of the present invention. FIG. 1 shows a cross section of the stacked type secondary battery during charging. The stacked type secondary battery 10a shown in FIG. 1 has a structure in which a substantially rectangular power generating element 21 in which a charge / discharge reaction actually proceeds is sealed inside a laminate film 29 that is a battery exterior body. Here, the power generating element 21 has a structure in which a negative electrode, a solid electrolyte layer 17, and a positive electrode are stacked. The negative electrode has a structure in which a negative electrode current collector 11', a negative electrode active material layer 13 made of lithium metal deposited on the surface of the negative electrode current collector 11', and a negative electrode intermediate layer 14 arranged between the negative electrode active material layer 13 and the solid electrolyte layer 17 are stacked. The positive electrode has a structure in which a positive electrode active material layer 15 is disposed on the surface of a positive electrode collector 11". The negative electrode, solid electrolyte layer, and positive electrode are laminated in this order, with the negative electrode intermediate layer 14 and the adjacent positive electrode active material layer 15 facing each other with the solid electrolyte layer 17 interposed therebetween. As a result, the adjacent negative electrode, solid electrolyte layer, and positive electrode constitute one unit cell layer 19. Therefore, the stacked secondary battery 10a shown in FIG. 1 can be said to have a structure in which a plurality of unit cell layers 19 are laminated and electrically connected in parallel. A negative electrode current collector 25 and a positive electrode current collector 27 that are electrically connected to the respective electrodes (negative electrode and positive electrode) are attached to the negative electrode current collector 11' and the positive electrode current collector 11", respectively, and have a structure in which they are sandwiched between the ends of the laminate film 29 and led out of the laminate film 29. A restraining pressure is applied to the stacked secondary battery 10a in the stacking direction of the power generating element 21 by a pressure member (not shown). Therefore, the volume of the power generating element 21 is kept constant.

[0014] Hereinafter, the main components of the all-solid-state battery according to this embodiment will be described.

[0015] [Current collector] The current collectors (negative electrode current collector, positive electrode current collector) have a function of mediating the movement of electrons from the electrode active material layers (negative electrode active material layer, positive electrode active material layer). There is no particular limitation on the material constituting the current collectors. For example, metals such as aluminum, nickel, iron, stainless steel, titanium, and copper, and conductive resins can be used as the material constituting the current collectors. There is also no particular limitation on the thickness of the current collectors, but an example is 10 to 100 μm.

[0016] [Negative electrode active material layer] The all-solid-state battery according to the present embodiment is a so-called lithium precipitation type battery in which lithium metal is precipitated on the negative electrode current collector during charging. The layer made of lithium metal precipitated on the negative electrode current collector during charging is the negative electrode active material layer of the lithium secondary battery, which is the all-solid-state battery according to the present embodiment. Therefore, the thickness of the negative electrode active material layer increases with the progress of the charging process, and the thickness of the negative electrode active material layer decreases with the progress of the discharging process. The negative electrode active material layer may not be present during full discharging, but in some cases, a negative electrode active material layer made of a certain amount of lithium metal may be placed during full discharging. The thickness of the negative electrode active material layer (lithium metal layer) during full charging is not particularly limited, but is usually 0.1 to 1000 μm. In one embodiment, the all-solid-state battery is a full precipitation type battery in which the negative electrode active material layer does not exist during full discharging.

[0017] [Negative electrode intermediate layer] The negative electrode intermediate layer is a layer interposed between the negative electrode active material layer and the solid electrolyte layer, and contains a lithium reactive material, such as a material capable of absorbing and releasing lithium ions or a metal capable of alloying with lithium during charging.

[0018] The material capable of absorbing and releasing lithium ions is not particularly limited, but is preferably a carbon material. Specific examples of the carbon material include carbon black (specifically, acetylene black, Ketjen Black (registered trademark), furnace black, channel black, thermal lamp black, etc.), carbon nanotubes (CNT), graphite, hard carbon, etc. Among them, carbon black is preferred, and at least one selected from the group consisting of acetylene black, Ketjen Black (registered trademark), furnace black, channel black, and thermal lamp black is more preferred.

[0019] Examples of metals that can be alloyed with lithium include In, Al, Si, Sn, Mg, Au, Ag, and Zn. Among these, In, Si, Sn, and Ag are preferred, and Ag is more preferred.

[0020] When the carbon material is in a particulate form, the average particle diameter (average primary particle diameter) is, for example, 10 nm to 200 nm, preferably 15 nm to 150 nm, and more preferably 20 nm to 100 nm. When the metal is in a particulate form, the average particle diameter is, for example, 10 nm to 500 nm, preferably 20 nm to 300 nm, more preferably 30 nm to 200 nm, and even more preferably 40 nm to 100 nm. In this specification, the average particle diameter of the carbon material and metal particles is the 50% cumulative diameter (D) of the particle diameters of the particles observed in several to several tens of fields of view when the cross section of the layer containing the particles is observed with a scanning electron microscope (SEM) (the maximum distance among the distances between any two points on the contour line of the observed particles). 50 )

[0021] The lithium reactive material may be used alone or in combination of two or more kinds. In a preferred embodiment, a material capable of absorbing and releasing lithium ions and a metal capable of alloying with lithium are used in combination. This ensures sufficient strength and lithium ion conductivity of the negative electrode intermediate layer. More specifically, it is preferred to use nanoparticles made of In, Si, Sn, or Ag in combination with carbon black, and more preferred to use nanoparticles made of Ag in combination with carbon black. When a material capable of absorbing and releasing lithium ions and a metal capable of alloying with lithium are used in combination, the compounding ratio (mass ratio) of these is not particularly limited, but the material capable of absorbing and releasing lithium ions:metal capable of alloying with lithium (mass ratio) is preferably 10:1 to 1:1, more preferably 5:1 to 2:1.

[0022] The content of the lithium reactive material in the negative electrode intermediate layer (when two or more materials are used in combination, this refers to the total content of those materials; the same applies below) is not particularly limited, but is preferably within the range of 50 to 100 mass%, more preferably within the range of 70 to 100 mass%, even more preferably within the range of 85 to 99 mass%, and particularly preferably within the range of 90 to 99 mass%, relative to the total mass of the negative electrode intermediate layer.

[0023] The negative electrode intermediate layer may be made of only the lithium reactive material, if a free-standing film can be produced using only the lithium reactive material, but may also contain a binder as necessary. The type of binder is not particularly limited, and any binder known in the art may be appropriately used. Examples include polyvinylidene fluoride (PVDF) (including compounds in which hydrogen atoms are substituted with other halogen elements), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), and carboxymethyl cellulose.

[0024] The content of the binder in the negative electrode intermediate layer is not particularly limited, but is preferably within a range of 1 to 15 mass % and more preferably within a range of 5 to 10 mass % relative to the total mass of the negative electrode intermediate layer. If the binder content is 1 mass % or more, a negative electrode intermediate layer having sufficient strength can be formed. If the binder content is 15 mass % or less, a negative electrode intermediate layer having sufficient lithium ion conductivity can be formed.

[0025] The porosity of the negative electrode intermediate layer is not particularly limited, but is, for example, 10 to 70%, preferably 20 to 60%. Within the above range, the effects of the present invention can be obtained more significantly. The porosity of the negative electrode intermediate layer can be estimated using the volume of the voids in the negative electrode intermediate layer measured by a mercury intrusion method using a mercury porosimeter described later, and the size and thickness of the negative electrode intermediate layer. The thickness of the negative electrode intermediate layer can be determined by SEM observation of the cross section.

[0026] The thickness of the negative electrode intermediate layer is not particularly limited, but is preferably 1 to 50 μm, more preferably 5 to 40 μm, and even more preferably 10 to 30 μm. When the thickness of the negative electrode intermediate layer is 1 μm or more, the function of the negative electrode intermediate layer can be sufficiently exhibited. When the thickness of the negative electrode intermediate layer is 50 μm or less, a decrease in energy density can be suppressed.

[0027] [Solid electrolyte layer] The solid electrolyte layer is interposed between the negative electrode and the positive electrode and contains a solid electrolyte (usually as a main component). The solid electrolyte contained in the solid electrolyte layer is not particularly limited, and any solid electrolyte known in the art can be appropriately adopted. As an example, LPS (Li 2 SP 2 S 5 ), Li 6 P.S. 5 X (wherein X is Cl, Br or I), Li 7 P 3 S 11 , Li 3.2 P 0.96 S and Li 3 P.S. 4Examples of sulfide solid electrolytes include sulfide solid electrolytes such as those described above. These sulfide solid electrolytes are preferably used because they have excellent lithium ion conductivity and can follow the volume change of the electrode active material accompanying charging and discharging due to their low bulk modulus. These solid electrolytes may be used alone or in combination of two or more. Of course, solid electrolytes other than those mentioned above may also be used.

[0028] The content of the solid electrolyte in the solid electrolyte layer is preferably 50 to 100 mass %, and more preferably 90 to 100 mass %.

[0029] The solid electrolyte layer may further contain a binder in addition to the solid electrolyte. The binder that can be used in the solid electrolyte layer may be the same as that described in the negative electrode intermediate layer.

[0030] The thickness of the solid electrolyte layer varies depending on the intended configuration of the all-solid-state battery, but is usually 0.1 to 1000 μm, and preferably 10 to 40 μm.

[0031] [Cathode active material layer] The positive electrode active material layer essentially contains a positive electrode active material, and may contain a binder, a conductive assistant, and a solid electrolyte as necessary.

[0032] The type of the positive electrode active material contained in the positive electrode active material layer is not particularly limited, but a lithium-containing metal oxide is preferable. A specific example of the lithium-containing metal oxide is LiCoO 2 , LiMnO 2 , LiNiO 2 , Li(Ni-Mn-Co)O 2 Layered rock salt active materials such as LiMn 2 O 4 , LiNi 0.5 Mn 1.5 O 4 Spinel-type active materials such as LiFePO 4 , LiMnPO 4 Olivine-type active materials such as Li 2 FeSiO 4 , Li2 MnSiO 4 Examples of lithium-containing metal oxides other than those mentioned above include Si-containing active materials such as Li 4 Ti 5 O 12 , LiVO 2 Among them, Li(Ni-Mn-Co)O 2 And those in which a part of these transition metals is replaced by other elements (NMC composite oxides) are preferably used as the positive electrode active material. These positive electrode active materials may be used alone or in combination of two or more kinds.

[0033] The content of the positive electrode active material in the positive electrode active material layer is, for example, 40 to 100 mass %, preferably 50 to 100 mass %, more preferably 55 to 95 mass %, and further preferably 60 to 90 mass %.

[0034] The positive electrode active material layer preferably further contains a solid electrolyte. As a specific form of the solid electrolyte contained in the positive electrode active material layer, the form described in the section on the solid electrolyte layer can be adopted in the same manner. A sulfide solid electrolyte is preferably used because it has excellent lithium ion conductivity and a low bulk modulus, and therefore can follow the volume change of the positive electrode active material accompanying charge and discharge. There is no particular limit to the content of the solid electrolyte in the positive electrode active material layer, but it is, for example, 1 to 50 mass%, preferably 10 to 40 mass%, and more preferably 20 to 40 mass%.

[0035] The positive electrode active material layer may further contain a binder and / or a conductive assistant. The binder that can be used in the positive electrode active material layer is the same as that described in the negative electrode intermediate layer. Examples of the conductive assistant include metals such as aluminum, stainless steel (SUS), silver, gold, copper, and titanium, alloys or metal oxides containing these metals, carbon fibers (specifically, vapor grown carbon fibers (VGCF), polyacrylonitrile carbon fibers, pitch carbon fibers, rayon carbon fibers, activated carbon fibers, etc.), carbon nanotubes (CNTs), and carbon black (specifically, acetylene black, Ketjen Black (registered trademark), furnace black, channel black, thermal lamp black, etc.), but are not limited thereto. In addition, a particulate ceramic material or a resin material coated with the above-mentioned metal material by plating or the like can also be used as a conductive assistant. The content of the binder and / or conductive assistant in the positive electrode active material is not particularly limited, and conventionally known knowledge can be appropriately adopted.

[0036] The thickness of the positive electrode active material layer varies depending on the intended configuration of the all-solid-state battery, but is usually 0.1 to 1000 μm, and preferably 10 to 40 μm.

[0037] Next, the manufacturing method according to the present embodiment will be described. The all-solid-state battery manufactured by the manufacturing method according to the present embodiment has undergone an initial charging step. Here, in this specification, the structure to which the initial charging step is applied is referred to as an "all-solid-state battery precursor". This "all-solid-state battery precursor" has the same configuration as the all-solid-state battery manufactured by the manufacturing method according to the present embodiment (specifically, it essentially has the above-mentioned positive electrode active material layer, solid electrolyte layer, negative electrode intermediate layer, and negative electrode current collector). The manufacturing method according to the present embodiment is broadly divided into a stage 1 in which an all-solid-state battery precursor having the above-mentioned configuration is prepared, and a stage 2 in which the all-solid-state battery precursor is subjected to an initial charge. The initial charging step performed in the stage 2 essentially has a first step (charging step) and a second step (holding step) (these details will be described later). By this initial charging step, charging is performed from the uncharged state after the stage 1 to a predetermined capacity, and aging is performed. After this initial charging step, a discharging step, which is an optional step, may be further performed. In addition, the above-mentioned initial charging step may be an additional charging step after the first step and the second step, and the additional charging step may be used to charge, for example, to a fully charged state. The manufacturing method according to the present embodiment is characterized in stage 2 in which the all-solid-state battery precursor is subjected to the initial charging step (and a discharging step as necessary). Meanwhile, the method for producing the all-solid-state battery precursor in stage 1 is not particularly limited, and therefore a detailed description of stage 1 will be omitted.

[0038] [Charging process (first process) and holding process (second process)] In the step 2 of the manufacturing method according to the present embodiment, the capacity Cx [mAh / cm 2 ] of the lithium reactive material per unit area of ​​the negative electrode intermediate layer is determined for the all-solid-state battery precursor having the above-mentioned configuration. 2 ], and the capacity Cx and the capacity Cy [mAh / cm2] based on the voids in the negative electrode intermediate layer per unit area 2 ] and (Cx+Cy) [mAh / cm 2 and a second step of holding the all-solid-state battery precursor that has been subjected to the first step at a holding temperature T for t hours, wherein (T[°C]+273)×ln(t[hours])≧1100 is satisfied.

[0039] As in Patent Document 1 described above, in a lithium deposition type all-solid-state battery, a technique is known in which a negative electrode intermediate layer containing amorphous carbon or the like is provided between a negative electrode current collector and a solid electrolyte layer. In a lithium deposition type all-solid-state battery, before charging (especially before the first charge), the negative electrode intermediate layer is in a state where lithium does not exist. That is, the negative electrode intermediate layer is in a state where there are very few conduction paths for lithium ions. It has been found that when charging and discharging are performed in this state, current concentration may occur, leading to a short circuit, or a sufficient charge-discharge capacity may not be obtained. On the other hand, according to the manufacturing method of the present embodiment, by performing a predetermined first charging step to form a sufficient conduction path for lithium ions in the negative electrode intermediate layer, an excellent charge-discharge capacity can be obtained in a lithium deposition type all-solid-state battery.

[0040] The all-solid-state battery precursor produced in Step 1 is in an uncharged state (a state in which lithium is not contained in the lithium-reactive material contained in the negative electrode intermediate layer (for example, a state in which lithium is not occluded in a material capable of occluding and releasing lithium ions, and / or a state in which lithium is not alloyed with a metal capable of alloying with lithium)). Here, for the first time in the charging step (the first step) of Step 2, lithium ions move from the positive electrode to the negative electrode. At this time, first, lithium is stored in the negative electrode intermediate layer. The storage of lithium in the negative electrode intermediate layer includes the following forms. (i) When the lithium-reactive material contained in the negative electrode intermediate layer includes a material capable of occluding and releasing lithium ions such as a carbon material, lithium is occluded in the material. (ii) When the lithium-reactive material contained in the negative electrode intermediate layer includes a metal capable of alloying with lithium, the metal and lithium are alloyed. (iii) Lithium metal precipitates in the void portion of the negative electrode intermediate layer. Then, after lithium corresponding to the capacity of the lithium-reactive material and the voids in the negative electrode intermediate layer is stored, lithium metal (negative electrode active material layer) precipitates between the negative electrode intermediate layer and the negative electrode current collector.

[0041] In the manufacturing method of the present embodiment, the capacity C [mAh / cm of the all-solid-state battery precursor at the end point of charging (the time when charging is stopped) in the first step 2satisfies Cx < C ≤ Cx + Cy. Here, Cx [mAh / cm 2 is the capacity of the lithium reactive material per unit area of the negative electrode intermediate layer. Cy [mAh / cm 2 is the capacity based on the voids per unit area of the negative electrode intermediate layer, which is the capacity of lithium when the voids in the negative electrode intermediate layer are filled with lithium. By satisfying the above formula, a sufficient amount of lithium is stored (occluded, alloyed, precipitated) in the negative electrode intermediate layer. Note that the capacity of the negative electrode intermediate layer of the all-solid-state battery precursor in the uncharged state is 0 [mAh / cm 2 .

[0042] The lithium stored (occluded, alloyed, precipitated) in the negative electrode intermediate layer by the charging process (first process) can move (diffuse) through the negative electrode intermediate layer by performing the holding process (second process) in stage 2. As a result, lithium exists uniformly throughout the negative electrode intermediate layer. As a result, lithium ion conductivity is uniformly imparted to the negative electrode intermediate layer.

[0043] As described above, during charging of the lithium precipitation type all-solid-state battery, after lithium corresponding to the capacity of the lithium reactive material and voids in the negative electrode intermediate layer is stored, lithium metal (negative electrode active material layer) precipitates between the negative electrode intermediate layer and the negative electrode current collector. In the all-solid-state battery manufactured by the method of this embodiment, by the above first process and second process, a sufficient amount of lithium is stored in the negative electrode intermediate layer, and a lithium ion conduction path exists throughout the negative electrode intermediate layer. Therefore, during charging of the all-solid-state battery, lithium ions can be efficiently moved from the solid electrolyte layer to the negative electrode current collector, and the lithium metal (negative electrode active material layer) precipitated by charging becomes more uniform. In addition, since the strength in the negative electrode intermediate layer also becomes uniform, even when minute dendrites are generated in the lithium metal (negative electrode active material layer), their growth is suppressed. Therefore, in the lithium precipitation type all-solid-state battery, a more reliable short-circuit suppression effect is exhibited, and it is considered that the charge and discharge capacity of the battery can be improved.

[0044] [Charging process (first process)] <Capacity of lithium reactive material per unit area of the negative electrode intermediate layer> In this specification, the capacity Cx [mAh / cm 2 ] of the lithium reactive material per unit area of ​​the negative electrode intermediate layer 2 ] is a value calculated by multiplying the capacity per unit mass of the lithium reactive material contained per unit area of ​​the negative electrode intermediate layer by the mass of the lithium reactive material contained per unit area of ​​the negative electrode intermediate layer. The capacity per unit mass of each lithium reactive material is determined by the following method. 0.1 g of sample A, which is the lithium reactive material to be measured, is weighed out, placed in an SLD sleeve (Φ10), and clamped at both ends with SLD pins plated with hard Cr. A pellet made of sample A is produced by pressing at room temperature (25°C) for 1 minute at a pressure of 390 MPa. In addition, Li as a solid electrolyte is weighed out, and the capacity per unit mass of each lithium reactive material is calculated by the following method. 0.1 g of sample A, which is the lithium reactive material to be measured, is weighed out, placed in an SLD sleeve (Φ10), and clamped at both ends with SLD pins plated with hard Cr. A pellet made of sample A is produced by pressing at room temperature (25°C) for 1 minute at a pressure of 390 MPa. 6 P.S. 5 Weigh out 0.1 g of Cl, and prepare a solid electrolyte pellet in the same manner as above. SUS foil as a current collector, a pellet made of sample A, a solid electrolyte pellet, lithium metal as a counter electrode, and SUS foil as a current collector are stacked in this order to prepare a half cell for capacity measurement. A confining pressure of 3 MPa is applied in the stacking direction of the half cell for capacity measurement using a pressure member, and a current of 1.5 [mA / cm2] is applied at a temperature of 60°C. 2 ], lithium ions are transferred from the lithium metal to the pellet made of sample A. The behavior of the cell voltage during this process is measured, and the current capacity [mAh] of the lithium reactive material is determined from this behavior. The cut-off voltage differs depending on the type of lithium reactive material, but the point at which the cell voltage drops sharply is taken as the cut-off voltage. The time T (h) from the start of charging to cut-off and the constant charging current of 1.5 [mA / cm 2 ] divided by the mass of sample A used in the measurement (0.1 g) is the capacity per unit mass of sample A [mA / (g cm 2 The mass M (g) of the lithium reactive material contained per unit area of ​​the negative electrode intermediate layer and the capacity per unit mass of each material calculated above [mA / (g cm 2 )] is the product of Cx [mAh / cm 2When two or more types of lithium reactive materials are contained in the negative electrode intermediate layer, the capacity per unit mass is calculated for each material by the above method, and the product of this and the mass of each material contained per unit area of ​​the negative electrode intermediate layer is calculated. The products calculated for all materials are then summed to obtain the capacity Cx [mAh / cm 2 ] can be obtained.

[0045] <Capacity based on voids per unit area of ​​negative electrode intermediate layer> In this specification, the capacity C based on the void per unit area of ​​the negative electrode intermediate layer y [mAh / cm 2 ] is calculated using the following method.

[0046] First, the volume of the voids (pores) in the negative electrode intermediate layer (total pore volume) was measured by the mercury intrusion method using a mercury porosimeter. Specifically, mercury was injected into the voids in the negative electrode intermediate layer to be measured, and the volume of the voids in the negative electrode intermediate layer V (total pore volume) [cm 3 The measurement device used was a Micromeritics Autopore IV 9510, with a pore size range of 0.003 to 500 μm, a mercury contact angle of 130°, and a mercury surface tension of 485 dynes / cm. The volume of the voids in the negative electrode intermediate layer (total pore volume) V [cm 3 ], the theoretical capacity of lithium per unit volume (2.062 × 10 -3 [mAh / cm 3 ]) and multiplied by the unit area [cm 2 ] is the capacity C y [mAh / cm 2 ].

[0047] If the capacity C of the all-solid-state battery precursor at the end of the first step is equal to or less than the capacity Cx of the lithium reactive material per unit area of ​​the negative electrode intermediate layer, it is not possible to store a sufficient amount of lithium to form a conductive path for lithium ions in the negative electrode intermediate layer. As a result, lithium ions that have moved from the solid electrolyte layer side during charging of the battery cannot move to the negative electrode current collector, and may precipitate between the negative electrode intermediate layer and the solid electrolyte layer, leading to a short circuit or a decrease in performance. On the other hand, if the capacity C of the all-solid-state battery precursor at the end of the first step exceeds the sum (Cx+Cy) of the above capacity Cx and the capacity Cy based on the voids per unit area of ​​the negative electrode intermediate layer, lithium is stored in the lithium reactive material and voids in the negative electrode intermediate layer, and at the same time, lithium metal is precipitated between the negative electrode intermediate layer and the negative electrode current collector. The precipitated lithium metal reacts with residual moisture inside the battery exterior body to produce lithium metal that is not involved in the battery reaction, leading to a decrease in capacity.

[0048] The capacity C of the all-solid-state battery precursor at the end of the first step is preferably Cx+0.1×Cy or more, more preferably Cx+0.2×Cy or more, and even more preferably Cx+0.3×Cy or more. Within the above range, the effects of the present invention can be obtained more significantly. Furthermore, the capacity C of the all-solid-state battery precursor at the end of the first step is preferably Cx+0.8×Cy or less, more preferably Cx+0.7×Cy or less, and even more preferably Cx+0.6×Cy or less. Within the above range, the effects of the present invention can be obtained more significantly.

[0049] The charging method in the first step is not particularly limited. The current density during charging is also not particularly limited, but is, for example, 0.1 to 10 mA / cm. 2 and preferably 1 to 5 mA / cm 2 The charging rate is not particularly limited and is, for example, 0.001 to 2 C, preferably 0.005 to 1 C, and more preferably 0.005 to 0.1 C. The charge cut-off voltage in the first step is also not particularly limited and is, for example, 2.8 to 3.2 V.

[0050] The current density during charging may be constant or may vary from the start to the end of charging, but is preferably constant. If the current density during charging varies, it is preferable that the maximum value of the current density is within the above range.

[0051] The first step is preferably carried out under an inert gas atmosphere, although there is no particular limitation thereto. The temperature conditions for carrying out the first step are also not particularly limited, and are, for example, 20 to 80°C, and preferably 50 to 70°C.

[0052] In the manufacturing method according to the present embodiment, it is more preferable to perform the first step and the second step described later while applying a restraining pressure to the all-solid-state battery precursor. That is, in the manufacturing method according to the present embodiment, it is preferable to perform the first step and the second step in a state in which the all-solid-state battery precursor further includes a restraining member that restrains the power generating element in the stacking direction, and the restraining pressure in the stacking direction of the power generating element is 0.1 MPa or more. By performing charging and aging while applying the restraining pressure in this way, lithium ion conductivity is imparted more uniformly to the negative electrode intermediate layer, and the lithium metal (negative electrode active material layer) precipitated thereafter becomes more uniform. In addition, since the strength of the negative electrode intermediate layer becomes more uniform, even if fine dendrites are generated in the lithium metal (negative electrode active material layer), their growth is suppressed. Therefore, in the lithium precipitation type all-solid-state battery, it is possible to further suppress short circuits, and a higher charge / discharge capacity can be obtained. From this viewpoint, the restraining pressure is more preferably 0.2 MPa or more, more preferably 1.0 MPa or more, and particularly preferably 3.0 MPa or more. The upper limit of the confining pressure is not particularly limited, but is, for example, 15 MPa or less, and preferably 10 MPa.

[0053] [Holding (aging) process (second process)] The second step is a step of holding the all-solid-state battery precursor that has been subjected to the first step at a holding temperature T and a holding time t, Formula 1: (T[℃]+273)×ln(t[time])≧1100 Meet the following.

[0054] The all-solid-state battery precursor that has undergone the first step has the above-mentioned predetermined capacity C. In the second step, the all-solid-state battery precursor having the above-mentioned capacity C is held at a holding temperature T and a holding time t while charging is stopped. It is preferable that no other charging step and / or discharging step is included between the first step and the second step. That is, it is preferable that the second step is carried out following the first step.

[0055] The second step may be composed of multiple steps with different holding temperatures. In this case, (T[℃]+273)×ln(t[time]) is calculated for each step, and the sum is set to 1100 or more.

[0056] By carrying out the holding step, the diffusion of lithium stored in the negative electrode intermediate layer progresses, and the lithium is uniformly present inside the negative electrode intermediate layer. Since the diffusion coefficient depends on the temperature and the diffusion distance is the product of time and the diffusion coefficient, the higher the holding temperature and the longer the holding time, the more the lithium diffusion progresses. In the method of this embodiment, by carrying out the second step so that the holding temperature T and the holding time t satisfy the above formula 1, the diffusion of lithium in the negative electrode intermediate layer progresses sufficiently, and a conduction path of lithium ions can be effectively generated in the negative electrode intermediate layer. As a result, when the obtained all-solid-state battery is charged, the lithium ions can efficiently move from the solid electrolyte layer to the negative electrode current collector, and the charge / discharge capacity of the battery can be improved.

[0057] When the value of (T [°C] + 273) × ln (t [hour]) is less than 1100, the diffusion of lithium stored in the negative electrode intermediate layer becomes insufficient. Therefore, in the negative electrode intermediate layer, a region remains where the formation of the lithium ion conduction path is still insufficient. Such a region becomes a bottleneck for lithium ion conduction especially when charging at a high rate, and the lithium ions moving from the solid electrolyte layer side cannot reach the negative electrode current collector and may precipitate between the negative electrode intermediate layer and the solid electrolyte layer. As a result, short circuit or capacity reduction may occur. Also, if a region where the formation of the lithium ion conduction path remains insufficient remains, lithium may be occluded in the region when charging the obtained battery, and the capacity may decrease.

[0058] Preferably, the value of (T [°C] + 273) × ln (t [hour]) is 1150 or more, more preferably 1200 or more. When it is in the above range, the effects of the present invention can be obtained more remarkably. Also, the upper limit value of the value of (T [°C] + 273) × ln (t [hour]) is not particularly limited, but is, for example, 1500 or less, preferably 1400 or less, more preferably 1350 or less. When it is in the above range, the effects of the present invention can be obtained more remarkably. In particular, when the value of (T [°C] + 273) × ln (t [hour]) is 1350 or less, it is preferable because it is possible to suppress the lithium stored in the negative electrode intermediate layer from reacting with impurities such as residual moisture inside the battery exterior and becoming inactivated, resulting in a decrease in capacity. That is, in a preferred embodiment of the present invention, in the second step, the holding temperature T and the holding time t satisfy the formula 2: (T [°C] + 273) × ln (t [hour]) ≤ 1350.

[0059] The holding temperature in the second step is not particularly limited as long as it satisfies the above formula 1, but is preferably 40°C or higher, more preferably 45°C or higher, even more preferably 50°C or higher, even more preferably 55°C or higher, and particularly preferably 60°C or higher. In the above range, the lithium filled in the negative electrode intermediate layer is more effectively diffused, and the negative electrode intermediate layer is more effectively imparted with lithium ion conductivity. Therefore, the effect of the present invention can be obtained more significantly. The upper limit of the holding temperature is, for example, 100°C or lower, for example, 80°C or lower, preferably 70°C or lower, and more preferably 65°C or lower. It is preferable that the upper limit of the holding temperature is set so as to satisfy the above formula 2.

[0060] The holding time in the second step is not particularly limited as long as it satisfies the above formula 1, but is, for example, 24 hours or more, for example, 25 hours or more, preferably more than 25 hours, preferably 30 hours or more, more preferably 35 hours or more, and even more preferably 40 hours or more. In the above range, the lithium filled in the negative electrode intermediate layer is more effectively diffused, and lithium ion conductivity is more effectively imparted to the negative electrode intermediate layer. Therefore, the effect of the present invention can be obtained more significantly. The upper limit of the holding time is, for example, 100 hours or less, for example, 80 hours or less, for example, 60 hours or less, for example, 55 hours or less, for example, 50 hours or less. It is preferable that the upper limit of the holding temperature is set so as to satisfy the above formula 2.

[0061] In a preferred embodiment of the present invention, the second step includes holding the all-solid-state battery precursor that has been subjected to the first step for 35 hours or more at a temperature range of 40 to 70° C. In this case, the temperature range is preferably 45 to 70° C., more preferably 50 to 65° C., even more preferably 55 to 65° C., and even more preferably 60 to 65° C. The holding time is preferably 35 to 60 hours, and more preferably 35 to 50 hours.

[0062] In the manufacturing process of conventional liquid-based lithium secondary batteries using organic electrolyte, an aging treatment may be performed by maintaining the battery at a constant temperature after the initial charge. This causes a reaction between the organic electrolyte and the surface of the negative electrode active material, forming an SEI film at the interface between the organic electrolyte and the negative electrode active material. It is believed that this SEI film facilitates the insertion and removal of lithium ions and suppresses the decomposition of the organic electrolyte, thereby improving the performance of the battery. On the other hand, it has been believed that aging is unnecessary for all-solid-state batteries that do not use organic electrolyte.

[0063] In a lithium deposition type all-solid-state battery, a negative electrode intermediate layer is usually provided between a negative electrode current collector and a solid electrolyte layer. The presence of the negative electrode intermediate layer suppresses the growth of dendrites from the lithium metal layer (negative electrode active material layer) when lithium metal is deposited between the negative electrode intermediate layer and the negative electrode current collector during charging, thereby preventing short circuiting of the battery and a decrease in capacity due to this. However, it has been found that high charge / discharge characteristics may not be obtained in a lithium deposition type all-solid-state battery having a negative electrode intermediate layer. The present invention has found that the reason for the failure to obtain high charge / discharge characteristics in such an all-solid-state battery is that a uniform and sufficient lithium ion conduction path is not formed inside the negative electrode intermediate layer. And, it has been found that, when manufacturing a lithium deposition type all-solid-state battery having a negative electrode intermediate layer, a lithium ion conduction path can be secured inside the negative electrode intermediate layer by performing the specified first and second steps, thereby improving the charge / discharge characteristics of the battery.

[0064] [Additional charging process] In the manufacturing method according to the present embodiment, in step 2, the all-solid-state battery precursor that has undergone the above-mentioned first and second steps may be subjected to one or more additional charging steps. Preferably, the all-solid-state battery precursor that has undergone the above-mentioned first and second steps is subjected to an additional charging step before the discharging step. It is more preferable to charge the all-solid-state battery precursor to a fully charged state (SOC 100%) by the additional charging step. That is, in a preferred embodiment of the present invention, the initial charging step in step 2 includes the first step, the second step, and an additional charging step.

[0065] The specific form of the additional charging step is not particularly limited. The charging rate is not particularly limited, and is, for example, 0.1 to 10 C, and preferably 0.1 to 5 C. In the additional charging step, the charging rate is preferably higher than the charging rate in the first step. The charging is not particularly limited, but is preferably performed at a constant current density.

[0066] The additional charging step is not particularly limited, but is preferably performed under an inert gas atmosphere. The temperature conditions during charging are also not particularly limited, and are, for example, 20 to 80°C, and preferably 50 to 70°C. In addition, it is preferable to charge while applying a binding pressure to the all-solid-state battery precursor. The means for applying the binding pressure and the preferred form of the binding pressure are the same as those described above.

[0067] [Discharge process] The manufacturing method according to the present embodiment may further include a discharging step of discharging the all-solid-state battery precursor that has been subjected to the first step, the second step, and the additional charging step, as necessary. In this case, it is preferable that the discharging step is not included between the start of the first step and the end of the additional charging step. It is also preferable that the additional charging step is performed to finally charge the battery to a fully charged state. By performing the discharging step, it is possible to suppress side reactions with impurities such as moisture in the cell. Therefore, a battery with an even higher capacity can be obtained.

[0068] The conditions for discharging are not particularly limited. The discharge rate is not particularly limited and is, for example, 0.05 to 5 C, and preferably 0.1 to 1 C. The current density during discharging is also not particularly limited and is, for example, 0.1 to 10 mA / cm. 2 and preferably 1 to 5 mA / cm 2 The discharge is not particularly limited, but is preferably performed at a constant current density. The discharge cut-off voltage is not particularly limited, but is, for example, 2.8 to 3.2 V.

[0069] The discharge step is preferably carried out under an inert gas atmosphere. The temperature conditions during discharge are not particularly limited, and are, for example, 20 to 80° C., and preferably 50 to 70° C. In addition, it is preferable to discharge while applying a restraining pressure to the all-solid-state battery precursor. The means for applying the restraining pressure and the preferred form of the restraining pressure are the same as those described above.

[0070] In a preferred embodiment, the capacity of the all-solid-state battery precursor is determined by the capacity Cx [mAh / cm 2 ] of the lithium reactive material per unit area of ​​the negative electrode intermediate layer. 2 In a preferred embodiment, the capacity of the all-solid-state battery precursor is determined so as to be equal to or greater than the capacity C [mAh / cm 2 ] of the all-solid-state battery precursor at the end point of the first step. 2 ] is not less than. By performing the discharge step under such conditions, the subsequent charging step can be performed while maintaining the negative electrode intermediate layer formed in the above-mentioned first charging step (i.e., in a state in which lithium is held in the negative electrode intermediate layer and lithium ion conductivity is ensured). This makes it possible to make the lithium metal (negative electrode active material layer) precipitated in the subsequent charging step more uniform. In addition, since the strength in the negative electrode intermediate layer also becomes more uniform, even if minute dendrites are generated in the lithium metal (negative electrode active material layer) in the subsequent charging step, their growth is suppressed. Therefore, a higher charge / discharge capacity can be obtained in a lithium precipitation type all-solid-state battery.

[0071] The following embodiments are also included within the scope of the present invention: the manufacturing method according to claim 1 having the features of claim 2; the manufacturing method according to claim 1 or 2 having the features of claim 3; the manufacturing method according to any one of claims 1 to 3 having the features of claim 4; the manufacturing method according to any one of claims 1 to 4 having the features of claim 5; the manufacturing method according to any one of claims 1 to 5 having the features of claim 6; the manufacturing method according to any one of claims 1 to 6 having the features of claim 7. EXAMPLES

[0072] The present invention will be described in more detail below with reference to examples. However, the technical scope of the present invention is not limited to the following examples. In the following, the operations were performed in a glove box with a dew point of -68°C or less. Furthermore, the instruments and devices used in the glove box were thoroughly dried in advance.

[0073] [Example 1] (Preparation of positive electrode) In a glove box with an argon atmosphere at a dew point of -68°C or less, LiNi 0.8 Mn 0.1 Co 0.1 O 2 , acetylene black as a conductive additive, and Li as a solid electrolyte. 6 P.S. 5 Cl was weighed out to a mass ratio of 50:30:20. These were mixed using an agate mortar, and then further stirred and mixed using a planetary ball mill. 2 parts by mass of styrene-butadiene rubber (SBR) as a binder was added to 100 parts by mass of the obtained mixed powder, and mesitylene was added as a solvent and mixed to prepare a positive electrode active material slurry. The positive electrode active material slurry was applied to the surface of an aluminum foil as a positive electrode current collector, dried, and pressed to obtain a positive electrode having a positive electrode active material layer (thickness 50 μm) on the surface of the positive electrode current collector.

[0074] (Preparation of solid electrolyte layer) In a glove box with an argon atmosphere at a dew point of -68°C or less, Li as a solid electrolyte was 6 P.S. 5 A solid electrolyte slurry was prepared by adding 2 parts by mass of SBR as a binder to 100 parts by mass of Cl, and adding mesitylene as a solvent and mixing them. The solid electrolyte slurry was applied to the surface of a stainless steel foil as a support and dried to obtain a solid electrolyte layer (thickness 30 μm).

[0075] (Preparation of negative electrode intermediate layer) Silver nanoparticles and carbon black nanoparticles were weighed and mixed in a mass ratio of 1:3. 0.5 parts by mass of SBR as a binder was added to 5 parts by mass of the obtained mixture, and mesitylene was added as a solvent and mixed to prepare a negative electrode intermediate layer slurry. The negative electrode intermediate layer slurry was applied to the surface of a stainless steel foil as a negative electrode current collector and dried to obtain a negative electrode intermediate layer.

[0076] (Preparation of cell precursor for evaluation) The positive electrode active material layer formed on the surface of the aluminum foil (positive electrode current collector) and the solid electrolyte layer formed on the surface of the stainless steel foil were stacked so that the exposed surface of the positive electrode active material layer and the exposed surface of the solid electrolyte layer faced each other, and transferred by cold isostatic pressing (CIP). After peeling off the stainless steel foil adjacent to the solid electrolyte layer, the solid electrolyte layer and the negative electrode intermediate layer formed on the surface of the stainless steel foil (negative electrode current collector) were stacked so that the exposed surface of the solid electrolyte layer and the exposed surface of the negative electrode intermediate layer faced each other, and transferred by cold isostatic pressing (CIP). Finally, an aluminum positive electrode tab and a nickel negative electrode tab were bonded to each of the aluminum foil (positive electrode current collector) and the stainless steel foil (negative electrode current collector) by an ultrasonic welding machine, and the obtained laminate was placed inside an aluminum laminate film and vacuum sealed to obtain a cell precursor for evaluation, which is a lithium deposition type all-solid-state battery precursor.

[0077] In the evaluation cell precursor, the thickness of the negative electrode intermediate layer was 15 μm and the porosity was 50%. The capacity Cx of the lithium reactive material (silver nanoparticles and carbon black nanoparticles) per unit area of ​​the negative electrode intermediate layer was 0.345 [mAh / cm 2 The capacity Cy based on the voids per unit area of ​​the negative electrode intermediate layer was 0.975 [mAh / cm 2 Cx + Cy was 1.320 [mAh / cm 2 ] was the case.

[0078] (Preparation of evaluation cells) The following initial charging was carried out at a temperature of 60° C. while applying a restraining pressure of 3 MPa using a pressure member in the stacking direction of the evaluation cell precursor produced above.

[0079] A pressure of 3 MPa was applied to the evaluation cell precursor in the stacking direction using a pressure member, and the charge capacity was increased to 0.638 [mAh / cm 2 Constant current charging was performed until the cell reached a constant current of 0.01×Cy (first step). Thereafter, charging was stopped and the cell was held at 60° C. for 40 hours (second step). This resulted in the evaluation cell of this example. At this time, the capacity of the evaluation cell precursor at the end point of the first step and the start point of the second step corresponds to Cx+0.3×Cy.

[0080] [Example 2] The charge capacity of the evaluation cell precursor was 1.028 [mAh / cm 2 The evaluation cell of this example was produced in the same manner as in Example 1, except that constant current charging was performed until the capacity reached Cx+0.7×Cy. In this example, the capacity of the evaluation cell precursor at the end point of the first step and the start point of the second step corresponds to Cx+0.7×Cy.

[0081] [Example 3] An evaluation cell of this example was produced in the same manner as in Example 1, except that the retention time at 60° C. after charging of the evaluation cell precursor was changed to 60 hours.

[0082] [Comparative Example 1] The charge capacity of the evaluation cell precursor was 0.345 [mAh / cm 2 An evaluation cell for this comparative example was produced in the same manner as in Example 1, except that constant current charging was performed until the capacity of the evaluation cell precursor reached Cx. In this comparative example, the capacity of the evaluation cell precursor at the end point of the first step and the start point of the second step corresponds to Cx.

[0083] [Comparative Example 2] The charge capacity of the evaluation cell precursor was 1.613 [mAh / cm 2 An evaluation cell for this comparative example was produced in the same manner as in Example 1, except that constant current charging was performed until the capacity of the evaluation cell precursor reached Cx+1.3×Cy in this comparative example. In this comparative example, the capacity of the evaluation cell precursor at the end point of the first step and the start point of the second step corresponds to Cx+1.3×Cy.

[0084] [Comparative Example 3] An evaluation cell of this comparative example was produced in the same manner as in Example 1, except that the retention time at 60° C. after charging of the evaluation cell precursor was changed to 25 hours.

[0085] [Comparative Example 4] An evaluation cell of this comparative example was produced in the same manner as in Example 1, except that the evaluation cell precursor was not held after charging.

[0086] <Evaluation of discharge capacity> Each evaluation cell was further charged at a constant current of 0.1 C at a temperature of 60° C. until the voltage reached 4.3 V, and then discharged at a constant current of 0.1 C until the voltage reached 2.5 V, and the discharge capacity at this time (first discharge capacity) was measured. The first discharge capacity obtained for each evaluation cell was calculated as a relative value when the discharge capacity of the evaluation cell of Example 1 was set to 100, and is shown in Table 1 below. Note that in Comparative Example 4, the discharge capacity could not be measured due to the occurrence of a short circuit.

[0087] [Table 1]

[0088] As shown in Table 1, the evaluation cells of Examples 1 to 3 obtained by carrying out the specified first and second steps show excellent discharge capacity. Therefore, it is understood that the method of the present invention can provide a lithium precipitation type all-solid-state battery with a higher capacity.

[0089] In contrast, in the cell of Comparative Example 1 in which charging was not performed in the first step to a capacity exceeding the capacity Cx of the lithium reactive material per unit area of ​​the negative electrode intermediate layer, sufficient capacity was not obtained even after aging in the second step. In the cell of Comparative Example 1, lithium was not sufficiently filled in the negative electrode intermediate layer in the first step, and it is considered that the distribution of lithium present in the negative electrode intermediate layer becomes uneven. Therefore, there are parts where lithium is not filled, and even after aging, the path of lithium ions is not uniformly formed in the negative electrode intermediate layer, and the deposition of lithium metal on the negative electrode current collector during subsequent charging becomes uneven, and it is considered that high capacity was not obtained.

[0090] On the other hand, sufficient capacity is not obtained when charging is performed in the first step beyond the sum of the capacity Cx of the lithium-reactive material per unit area of ​​the negative electrode intermediate layer and the capacity Cy based on the voids, as in Comparative Example 2. This is thought to be because lithium is not only filled into the negative electrode intermediate layer but also precipitates on the negative electrode current collector, and the precipitated lithium reacts with residual moisture inside the battery exterior body and becomes inactive, resulting in a decrease in capacity.

[0091] As in Comparative Example 3, when the holding temperature and holding time of the second step do not satisfy (T [°C] + 273) × ln (t [hours]) ≧ 1100, sufficient capacity is not obtained. In addition, when the second step is not performed as in Comparative Example 4, a short circuit occurs. When the specified second step is not performed, the diffusion of lithium filled in the negative electrode intermediate layer becomes insufficient, and the path of lithium ions from the solid electrolyte layer to the negative electrode current collector is not sufficiently formed. As a result, when the obtained all-solid-state battery is charged, lithium is precipitated between the negative electrode intermediate layer and the solid electrolyte layer, which is thought to lead to a decrease in performance and a short circuit. [Explanation of symbols]

[0092] 10a laminated secondary battery, 11' negative electrode current collector, 11” positive electrode current collector, 13 negative electrode active material layer, 14 negative electrode intermediate layer, 15 positive electrode active material layer, 17 solid electrolyte layer, 19 cell layer, 21 Power generation elements, 25 negative current collector, 27 Positive current collector, 29 Laminating film.

Claims

1. a positive electrode having a positive electrode active material layer containing a positive electrode active material; a negative electrode having a negative electrode current collector on which lithium metal is deposited during charging; a solid electrolyte layer interposed between the positive electrode and the negative electrode and containing a solid electrolyte; a negative electrode intermediate layer interposed between the negative electrode current collector and the solid electrolyte layer and including a lithium reactive material; A method for producing an all-solid-state battery comprising a power generating element having The capacity C [mAh / cm 2 ] of an all-solid-state battery precursor having the same configuration as the all-solid-state battery and in an uncharged state was ２ a first step of charging the battery up to A second step of holding the all-solid-state battery precursor having undergone the first step at a holding temperature T [° C.] and a holding time t [hours], The capacity C [mAh / cm ２ ] is represented by the following formula: Cx<C≦(Cx+Cy) where Cx [mAh / cm ２ ] is the capacity of the lithium reactive material per unit area of ​​the negative electrode intermediate layer, and Cy [mAh / cm ２ is a capacity based on the voids per unit area of ​​the negative electrode intermediate layer, The holding temperature T [° C.] and the holding time t [hours] are expressed by the following formula: A method for manufacturing an all-solid-state battery, which satisfies (T [°C] + 273) x ln (t [hours]) ≥ 1100.

2. The capacity C [mAh / cm ２ satisfies Cx + 0.3 × Cy ≤ C ≤ Cx + 0.7 × Cy, and is a method for manufacturing an all-solid-state battery according to claim 1.

3. The capacity C [mAh / cm ２ 3. The method for producing an all-solid-state battery according to claim 2, wherein Cx+0.3×Cy≦C≦Cx+0.6×Cy is satisfied.

4. The method for producing an all-solid-state battery according to claim 1 , wherein the holding temperature T [° C.] is 40° C. or higher.

5. The method for producing an all-solid-state battery according to claim 4 , wherein the holding temperature T [° C.] is 60° C. or higher.

6. The method for producing an all-solid-state battery according to claim 1 , wherein the holding time t [hours] is 40 hours or more.

7. The holding temperature T [° C.] and the holding time t [hours] are expressed by the following formula: The method for producing an all-solid-state battery according to claim 1, further satisfying (T [° C.] + 273) × ln (t [hours]) ≦ 1350.

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